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| Titel |
Longitudinal hotspots in the mesospheric OH variations due to energetic electron precipitation |
| VerfasserIn |
M. E. Andersson, P. T. Verronen, C. J. Rodger, M. A. Clilverd, S. Wang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 2 ; Nr. 14, no. 2 (2014-01-29), S.1095-1105 |
| Datensatznummer |
250118324
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| Publikation (Nr.) |
 copernicus.org/acp-14-1095-2014.pdf |
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| Zusammenfassung |
| Using Microwave Limb Sounder (MLS/Aura) and Medium Energy Proton and Electron
Detector (MEPED/POES) observations between 2005–2009, we study the
longitudinal response of nighttime mesospheric OH to radiation belt electron
precipitation. Our analysis concentrates on geomagnetic latitudes from
55–72° N/S and altitudes between 70 and 78 km. The aim of this study is
to better assess the spatial distribution of electron forcing, which is
important for more accurate modelling of its atmospheric and climate effects.
In the Southern Hemisphere, OH data show a hotspot, i.e. area of higher
values, at longitudes between 150° W–30° E, i.e. poleward
of the Southern Atlantic Magnetic Anomaly (SAMA) region. In the Northern
Hemisphere, energetic electron precipitation-induced OH variations are more
equally distributed with longitude. This longitudinal behaviour of OH can
also be identified using Empirical Orthogonal Function analysis, and is found
to be similar to that of MEPED-measured electron fluxes. The main difference
is in the SAMA region, where MEPED appears to measure very large electron
fluxes while MLS observations show no enhancement of OH. This indicates that
in the SAMA region the MEPED observations are not related to precipitating
electrons, at least not at energies >100 keV, but rather to instrument
contamination. Analysis of selected OH data sets for periods of different
geomagnetic activity levels shows that the longitudinal OH hotspot south of
the SAMA (the Antarctic Peninsula region) is partly caused by strong,
regional electron forcing, although atmospheric conditions also seem to play
a role. Also, a weak signature of this OH hotspot is seen during periods of
generally low geomagnetic activity, which suggests that there is a steady
drizzle of high-energy electrons affecting the atmosphere, due to the
Earth's magnetic field being weaker in this region. |
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